The present invention relates to curable coating compositions, and more particularly to low or ambient temperature curable coating compositions.
In the area of automotive refinish, repairing a defect in the original coating can involve sanding or grinding out the defect by mechanical means, or completely stripping the whole part or the whole vehicle of its original coating layers. This sanding or grinding process typically results in the exposure of bare metal which is then coated with a coating composition, usually a primer composition.
The automotive industry has, from the mid 1980's, been producing automobiles in which the major body panels are made of steel which has an outer surface treated with a zinc containing material. Typically the steel used is galvanized or galvanealed steel. Adhesion of coating compositions to these zinc coated steels may be poor. In some situations, chrome containing wash primers are used prior to the primer application to try to improve adhesion to these substrates. This incorporates an added step in the painting-process and utilizes chrome containing coatings which are not environmentally desirable. It would thus be desirable to have coating compositions that exhibit enhanced adhesion to substrates such as galvanized and galvanealed steel and would eliminate the need for chrome containing wash primers.